If you are working on trainings with a group and you want to add your own workouts into your program, you have to make sure you do not overdo it. You have to avoid back-to-back training days of the same muscle groups to prevent you from having injuries. Stew Smith suggests rules to help you maneuver through this routine while preparing for a special operations selection course.

Source: https://www.military.com/military-fitness/adding-your-own-workouts-mandatory-pt-remember-these-rules